Abstract:

Human voice production was studied using three methods: inverse filtering, digital high-speed imaging of the vocal folds, and electroglottography. The primary goal was to evaluate an inverse filtering method by comparing inverse filtered glottal flow estimates with information obtained by the other methods. More detailed examination of the human voice source behavior was also included in the work.

Material from two experiments was analyzed in this study. The data of the first experiment consisted of simultaneous recordings of acoustic speech signal, electroglottogram, and high-speed imaging acquired during sustained vowel phonations. Inverse filtered glottal flow estimates were compared with glottal area waveforms derived from the image material by calculating pulse shape parameters from the signals. The material of the second experiment included recordings of acoustic speech signal and electroglottogram during phonations of sustained vowels. This material was utilized for the analysis of the opening phase and the closing phase of vocal fold vibration.

The evaluated inverse filtering method was found to produce mostly reasonable estimates of glottal flow. However, the parameters of the system have to be set appropriately, which requires experience on inverse filtering and speech production. The flow estimates often showed a two-stage opening phase with two instants of rapid increase in the flow derivative. The instant of glottal opening detected in the electroglottogram was often found to coincide with an increase in the flow derivative. The instant of minimum flow derivative was found to occur mostly during the last quarter of the closing phase and it was shown to precede the closing peak of the differentiated electroglottogram.Ihmisen puheentuottoa tutkittiin kolmella menetelmällä: käänteissuodatuksella, äänihuulten digitaalisella suurnopeuskuvauksella ja elektroglottografialla. Päätavoitteena oli tarkastella erään käänteissuodatusmenetelmän toimintaa vertailemalla näillä menetelmillä saatua informaatiota äänihuulten värähtelystä. Lisäksi tutkittiin tarkemmin eräitä äänilähteen käyttäytymisen yksityiskohtia.